igS ABIOGENIC ORGANIC-CHEMICAL EVOLUTION 



On the other hand, organisms can absorb and consume such 

 substances, and metaboHse them to form parts of their own 

 bodies. They radically alter the whole course of the chemical 

 processes in their environment, not merely by their own 

 immediate activities, but also by means of the extremely 

 powerful catalysts which they produce — enzymes. 



We can therefore only judge of the transformations accom- 

 plished by the more or less complicated organic compounds 

 on the Earth at some time before the appearance of life by 

 analogy with phenomena which have been observed by arti- 

 ficially set up laboratory experiments. 



It is very easy to imagine the abiogenic development of 

 sugars and carbohydrates generally in the primaeval hydro- 

 sphere. The well-known synthesis carried out by A. But- 

 lerov"" as early as 1861 may serve as the starting point for 

 this. 



If one simply allows a solution of formaldehyde in lime 

 water to stand under ordinary laboratory conditions, con- 

 densation occurs and one obtains a syrup containing a sugar- 

 like substance which Butlerov called ' methylenitan '. The 

 chemical nature of this substance was not elucidated until 

 thirty years later. By similar means E. Fischer and J. TafeP" 

 prepared a syrup containing a mixture of sugars and isolated 

 from it a hexose (CeHiaOe) which they called ' acrose '. This 

 was optically inactive, as was to be expected from a labora- 

 tory synthesis. This optical inactivity was, however, merely 

 due to the fact that acrose was a racemic mixture of two 

 antipodal ketoses, natural D-fructose and L-fructose, its anti- 

 pode which is not met with in living nature. For this con- 

 densation reaction E. Fischer gave the following schematic 

 equation: 



CHnO + CHoO -1- CHoO + CH2O -fCHsO + CH^O-^ 



CHoOH.CHOH.CHOH.CHOH.CO.CH.OH 



However, it was later shown that the reaction seems to pass 

 through successive stages with the formation of intermediate 

 compounds containing fewer formaldehyde residues, in par- 

 ticular glvceraldehyde and dihydroxyacetone. 



By slightly altering the conditions of Butlerov's experi- 

 ment O. Loew^*^ first obtained ' formose ', a sweet syrup 



